Abstract not found

We address a global constraint for enforcing contiguity. Contiguity is the property that all of one kind of object in an array or list are grouped together; it is a one-dimensional discrete form of convexity. We present an implementation of this property in a concurrent constraint programming language. We adapt and apply the constraint propagation framework of [19] to analyse the contiguity property. In particular, the soundness of the implementation is proved and the forms of local consistency that are maintained by the implementation are identified. A complexity analysis shows that the implementation is optimal for achieving arc-consistency. However, an optimal implementation is not given for a stronger consistency condition, and we raise the possibility that an optimal implementation requires meta-level programming.

We develop a framework for addressing correctness and timeliness-of-propagation issues for reactive constraints - global constraints or user-defined constraints that are implemented through constraint propagation. The notion of propagation completeness is introduced to capture timeliness of constraint propagation. A generalized form of arc-consistency is formulated which unifies many local consistency conditions in the literature. We show that propagation complete implementations of reactive constraints achieve this arc-consistency when propagation quiesces. Finally, we use the framework to state and prove an impossibility result: that CHR cannot implement a common relation with a desirable degree of timely constraint propagation.

The timed concurrent constraint programming language (tccp in short) was introduced for modeling reactive systems. This language allows one to model in a very intuitive way typical ingredients of these systems such as timeouts, preemptions, etc. However, there is no natural way for modeling other desirable features such as functional computations, for example for calculating arithmetic results. In fact, although it is certainly possible to implement such kind of operations, each single step of the computation takes time in tccp, and avoiding interferences with the intended overall behavior of the (reactive) system is quite involved. In this paper, we propose an extension of tccp for modeling instantaneous computations which improves the expressiveness of the language, in the sense that operations that are cumbersome to implement in pure tccp, are executed by calling an efficient, external functional engine, while the tccp programmer can focus on the pure, and usually more complex, reactive part of the system. We also describe a case study which motivates the work, and discuss how the new capability presented here can also be used as a new tool for developers from the verification point of view.

This paper offers a critique of the framework of Constraint Satisfaction Problems. While this framework has been successful in studying search techniques, andhas inspired some constraint programming languages, it hassomeweaknesses that leave it not directly applicable to the study of complex constraints (including so-called global constraints) in constraint programming languages.In particular, it deals poorly with semantic relations whose consistency can be determined algorithmically. In this paper the philosophy of the CLP Scheme is applied to extend the CSP framework to a form more suitable for addressing complex constraints, where both constraint satisfaction and constraint solving have a role.

Abstract not found

The timed concurrent constraint programming language (tccp in short), was introduced for modeling reactive systems. This language allows one to model in a very intuitive way typical ingredients of these systems such as timeouts, preemptions, etc. However, there is no natural way for modeling other desirable features such as functional computations, for example for calculating arithmetic results. In fact, although it is certainly possible to implement such kind of operations, each single step takes time in tccp, and avoiding interferences with the intended overall behavior of the system is quite involved. In this paper, we propose an extension of tccp for modeling instantaneous computations which improves the expressiveness of the language, in the sense that operations that are cumbersome to implement in pure tccp, are executed by calling an efficient, external functional engine, while the tccp programmer can focus in the pure, and usually more complex, reactive part of the system. We also describe a case study which motivates the work, and discuss how the new capability presented here can also be used as a new tool for developers from the verification point of view.

Abstract. Extracting and visualizing information from biochemical databases is one of the most important challenges in biochemical research. The huge quantity and high complexity of the data available force the biologist to use sophisticated tools for extracting and interpreting accurately the information extracted from the database. These tools must define a graphical semantics associated to the data semantics in accordance with biologist usages. The aim of these tools is to display complex biochemical networks in a readable and understandable way. In this paper we define the notion of customizable representation model, which allows the biologist to change the graphical semantics associated to the data semantics. The approach is also generic since our graphical semantics is common to several kinds of biochemical networks. We also defined adaptive graph layout algorithms taking into account the particular semantics of biochemical networks. We show how we implemented these notions in the BioMaze project 1. 1

First of all, I would like to thank Prof. Dr. Claudia Leopold for giving me the opportunity to work in her group of “Programming Languages and Parallel Programming ” at University of Kassel and Prof. Dr. Emre Harmancı who accepted to be my supervisor. Prof. Leopold never let me alone even in the rest of my work in Turkey. Working at University of Kassel was a great experience for me. I feel fortunate to have helpful friends, Björn Knafla and Michael Süss who made my first time in Germany enjoyable. Thanks to Christiane Becker and Raffaele Biscosi for being so nice to me. I am grateful to Dr. Turgay Altılar who encouraged me for the presentations and helped me a lot. Special thanks to my parents who always supported me. December 2004 Ay¸se Beliz S¸enyüz iv TABLE OF CONTENTS ABBREVIATIONS viii